1. Field of the Invention
The invention relates to a pipette for a pipette system having a pipette and a syringe.
2. Description of Related Art
The known pipette, from which the invention proceeds (German Patent Application DE 199 17 907 A1), is particularly suitable with regard to handling within a pipette system because the replaceable syringe to be handled in each case with the pipette is insertable into the pipette and is removable again or discardable from said pipette in an axial manner. In a pure axial movement, the respective syringe is therefore directly insertable into the pipette as far as into the gripping positions of the flange of the cylinder and the plunger head of the plunger. The fixing in the gripping position is effected by means of radially adjustable cylinder gripping levers of the cylinder gripping device on the fastening portion of the cylinder, i.e., the flange thereof, and by means of radially adjustable plunger gripping levers of the plunger gripping device on the axially adjustable plunger adjusting device.
On account of the axial relative movement between the pipette and the syringe, the syringe can be held for picking-up in a fixed position anywhere, for example, in a stand. The pipette only has to be moved axially in relation to the syringe for the picking-up operation. To discard the syringe, it is also not necessary to grasp the syringe, it can simply fall out of the pipette axially or be discarded axially from the pipette. In this case the syringe is not touched, which means that the pipetted liquid cannot be contaminated by the hand.
In the case of the known pipette, addressed beforehand, two cylinder gripping levers and plunger gripping levers each are provided, the levers being located opposite each other, being under spring force in the gripping position and being movable into the release position in opposition to the spring force. An actuating device serves for actuating both pairs of levers, the actuating device having a central actuating element on the pipette housing which is actuatable from the outside.
In the case of the design outlined beforehand, the synchronization of multiple cylinder gripping levers and plunger gripping levers in the pipette housing is effected automatically by means of the force transmitting drives which proceed from the common, actuating element fixed in a stationary manner on the pipette housing. This is practical from a handling point of view. However, problems arise here, on the one hand, in the structural limitation to an additional, central actuating element which is externally actuatable and is fixed in a stationary manner on the pipette housing, and on the other hand, in the fact that it is not possible to release the cylinder gripping device and the plunger gripping device independently of each other.
In the case of other pipettes that are expedient from a handling point of view and have axial syringe coupling, there are similar problems with the actuation of the plunger gripping device and the cylinder gripping device as well as with the synchronization of the cylinder gripping levers (see, German Patent DE 43 41 229 C2 which corresponds to U.S. Pat. No. 5,620,660; German Patent Application DE 10 2005 023 203 A1 which corresponds to U.S. Pat. No. 7,731,908 B2, and European Patent EP 1 524 035 A1 which corresponds to U.S. Pat. No. 7,563,409 B2).
Along with the pipettes with axial syringe coupling explained beforehand, there are various designs of pipettes with radial syringe coupling (German Patent Application DE 199 63 141 A1 which corresponds to U.S. Pat. No. 6,540,964 B2; DE 29 26 691 A1 corresponds to U.S. Pat. No. 4,406,170; and the “HandyStep®” multi-dispenser by BRAND GMBH+CO KG, Wertheim from page 61 in the “GK800” general catalogue). The structural solutions proposed there for corresponding plunger gripping devices necessarily presuppose the plunger head being displaced in and out of the syringe by hand in a radially directed manner and are consequently not suitable for pipettes with axial syringe coupling.